How many of the following names are correct? Correct the incorrect names.
a. 3 -pentene
b. 2 -octene
c. 2 -vinylpentane
d. 1 -ethyl- 1 -pentene
e. 5 -ethylcyclohexene
f. 5 -chloro-3-hexene
g. 2 -ethyl-2-butene
h. $(E)-2$ -methyl-1-hexene
i. 2 -methylcyclopentene